Because it can literally put your life in danger! Let me explain.
This happened 6 years ago, I was still a college sophomore. It was around 5pm, and I was on the way home, waiting for either a jeep or an FX on the northbound side of Taft right across DLSU. It took quite a while on that particular day for a suitable ride to come by, I remember getting agitated.
A jeepney finally passed by and stopped. I caught a glimpse of an FX right behind it. While normally, I would opt straight for the FX, I decided against doing so. It was because I noticed there was a beautiful girl (a Lasallian, probably Chinese judging by face) who also took the jeepney. Two thoughts entered my mind: maybe I can get to know the girl; a beautiful girl would take the jeep why shouldn't I.
So I entered the jeep. I sat in the middle of the jeepney, diagonally from the girl - yeah, not the best positioning.
Right as we entered, 3 men also entered the jeepney. I remember that it was exactly 3. Two men sat beside me - one to my left, one to my right. The other man sat further out, near the exit. I remember feeling that these two men couldn't settle in their seats well, they were always jittery and shifting their weight around. I thought they just felt uncomfortable.
Then somewhere near Malvar, as the jeep slowed to a stop as it approached the stoplight, the man near the exit suddenly got up and covered the exit with his body. Feeling some sort of panic, I glanced around to see the two men to my left and right suddenly announce a holdup. Throw in a bunch of expletives to heighten the suspense. I can't remember if it was the man to my left or right who lifted a gun from his bag - probably the left. I think the gun was a revolver, details are hazy.
The man pointed the gun straight to my belly and told everyone to give their stuff. The man seemed to know how to carry the gun, and I don't think he was shaking - it seems he has done this before. At that moment, my life flashed before my eyes for a split second, but amazingly I remained calm. It's good I carry around an old phone (even by the standards of 6 yrs ago!) and only little cash in my wallet. So I calmly gave my stuff to the men. I think a few of the passengers were shouting and cursing the thieves. It's good that didn't irritate the thieves or else they could've opened fire (at me!).
They took phones and wallets from the passengers, and quickly got off the jeepney. I didn't lose much that day, but I noticed one young girl crying hard. She said that the phone the thieves stole was only a few days old and was expensive. When I got down at Binondo, the girl was still crying.
Two things I learned from this experience:
1. Always be alert. Watch out for people who can't sit still, eyes are darting around, and won't pay the driver.
2. When riding the jeepney, it's better to sit near the exit so you can get off when you sense something bad. Or the front seat.
OK, maybe "chasing" isn't the right term :)
Oh yeah, the thieves also stole from the beautiful girl.